fix: App Hanging on macOS

[filiph]

Description

Hi, this is almost certainly out of our reach but I decided to file it anyway just in case we see more of these and it turns out to be, in some way, connected to flutter_soloud.

Here's a StackTrace from the wild (using Sentry) that looks like either a mutex lock race condition in CoreAudio (macOS), or simply something taking very long (2 seconds).

 libsystem_kernel    0x18ed599c8  __psynch_mutexwait
  libsystem_pthread   0x18ed96e38  _pthread_mutex_firstfit_lock_wait
  libsystem_pthread   0x18ed94864  _pthread_mutex_firstfit_lock_slow
  libsystem_pthread   0x18ed9a164  _pthread_cond_wait
  CoreAudio           0x1924a1af0  HALB_Guard::WaitFor
  CoreAudio           0x192222ad4  HALB_IOThread::_WaitForState
  CoreAudio           0x192222e90  HALB_IOThread::StartAndWaitForState
  CoreAudio           0x192095d74  HALC_ProxyIOContext::_StartIO
  CoreAudio           0x192095950  HALC_ProxyIOContext::StartIOProc
  CoreAudio           0x192050ee4  HAL_HardwarePlugIn_DeviceStart
  CoreAudio           0x1921295dc  AudioDeviceStart_mac_imp
  CoreAudio           0x11c5aade0  <redacted>
  CoreAudio           0x11c5aabc4  <redacted>
  CoreAudio           0x11c6b7030  <redacted>
  AudioToolboxCore    0x191b800b4  AudioOutputUnitStart
  flutter_soloud      0x1009645ec  <redacted>
  flutter_soloud      0x100914994  <redacted>
  flutter_soloud      0x10096c0b0  <redacted>
  flutter_soloud      0x10096be98  <redacted>
  flutter_soloud      0x10091ae10  <redacted>
  App                 0x111ae1948  <redacted>
  App                 0x111ff33c4  <redacted>
  App                 0x111ff3288  <redacted>
  App                 0x111ff2e1c  <redacted>
  App                 0x111fef0f4  <redacted>
  App                 0x111b0e59c  <redacted>
  App                 0x111b0e434  <redacted>
  App                 0x111af441c  <redacted>
  App                 0x111af40cc  <redacted>
  App                 0x111fef4c0  <redacted>
  App                 0x111b15db4  <redacted>
  App                 0x111fef0f4  <redacted>
  App                 0x111ff00fc  <redacted>
  App                 0x111af3ec0  <redacted>
  App                 0x111af3dbc  <redacted>
  App                 0x111af3d80  <redacted>
  App                 0x111ae3f2c  <redacted>
  FlutterMacOS        0x102ebe070  <redacted>
  FlutterMacOS        0x102ebe680  <redacted>
  FlutterMacOS        0x10302ebdc  <redacted>
  FlutterMacOS        0x102d9c790  <redacted>
  FlutterMacOS        0x102d5bef4  <redacted>
  FlutterMacOS        0x102e72874  <redacted>
  FlutterMacOS        0x102e657b0  <redacted>
  FlutterMacOS        0x10259680c  <redacted>
  FlutterMacOS        0x1025f0508  <redacted>
  FlutterMacOS        0x1025ef568  <redacted>
  FlutterMacOS        0x1025ef1bc  <redacted>
  FlutterMacOS        0x1025ef5b0  <redacted>
  CoreFoundation      0x18ee389e4  __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__
  CoreFoundation      0x18ee38978  __CFRunLoopDoSource0
  CoreFoundation      0x18ee386e4  __CFRunLoopDoSources0
  CoreFoundation      0x18ee37374  __CFRunLoopRun
  CoreFoundation      0x18eef1358  _CFRunLoopRunSpecificWithOptions
  HIToolbox           0x19b892764  RunCurrentEventLoopInMode
  HIToolbox           0x19b895a8c  ReceiveNextEventCommon
  HIToolbox           0x19ba1f304  _BlockUntilNextEventMatchingListInMode
  AppKit              0x19371cd4c  _DPSBlockUntilNextEventMatchingListInMode
  AppKit              0x19322be30  _DPSNextEvent
  AppKit              0x193bc9744  -[NSApplication(NSEventRouting) _nextEventMatchingEventMask:untilDate:inMode:dequeue:]
  AppKit              0x193bc9450  -[NSApplication(NSEventRouting) nextEventMatchingMask:untilDate:inMode:dequeue:]
  AppKit              0x19322477c  -[NSApplication run]
  AppKit              0x1932106d8  NSApplicationMain
  giant_robot         0x1000f1e40  <redacted>
  0x18e9d1d54  <redacted>

I am not able to reproduce this.

Additional Context

# App Hanging: App hanging for at least 2000 ms.

**Issue ID:** 6962856949
**Project:** giant_robot
**Date:** 10/21/2025, 2:13:11 PM

## Tags

- **device:** Mac15,6
- **device.family:** macOS
- **dist:** 91
- **environment:** production
- **event.environment:** native
- **event.origin:** mac
- **level:** error
- **mechanism:** AppHang
- **os:** macOS 26.1.0
- **os.build:** 25B5062e
- **os.name:** macOS
- **os.rooted:** no
- **release:** [email protected]+91+Noa

## Exception

### Exception 1
**Type:** App Hanging
**Value:** App hanging for at least 2000 ms.

• Darwin Kernel Version 25.1.0: Sun Oct 5 21:07:37 PDT 2025; root:xnu-12377.40.120~10/RELEASE_ARM64_T6030
• arm64
• memory 18.0 GB

[alnitak]

Oh wow, that's weird :)

I could only make a few guesses.

It seems that AudioOutputUnitStart is trying to start initializing the output device, waiting for CoreAudio permission. But the permission isn't coming. Maybe the audio device is locked by some other apps?

Can't tell... Let's leave this issue open for a while and see if anyone else has any clues.